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Sökning: WFRF:(Kaya S.)

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1.
  • Aad, G, et al. (författare)
  • 2015
  • swepub:Mat__t
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2.
  • 2021
  • swepub:Mat__t
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3.
  • 2021
  • swepub:Mat__t
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4.
  • Bravo, L, et al. (författare)
  • 2021
  • swepub:Mat__t
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5.
  • Tabiri, S, et al. (författare)
  • 2021
  • swepub:Mat__t
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6.
  • Glasbey, JC, et al. (författare)
  • 2021
  • swepub:Mat__t
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7.
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9.
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10.
  • 2019
  • Tidskriftsartikel (refereegranskat)
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11.
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13.
  • Vogt, A., et al. (författare)
  • Isomers and high-spin structures in the N=81 isotones Xe-135 and Ba-137
  • 2017
  • Ingår i: PHYSICAL REVIEW C. - : AMER PHYSICAL SOC. - 2469-9985. ; 95:2
  • Tidskriftsartikel (refereegranskat)abstract
    • The high-spin structures and isomers of the N = 81 isotones Xe-135 and Ba-137 are investigated after multinucleon-transfer (MNT) and fusion-evaporation reactions. Both nuclei are populated (i) in Xe-136+ U-238 and (ii) Xe-136+ Pb-208 MNT reactions employing the high-resolution Advanced Gamma Tracking Array (AGATA) coupled to the magnetic spectrometer PRISMA, (iii) in the Xe-136+ Pt-198 MNT reaction employing the gamma-ray array GAMMASPHERE in combination with the gas-detector array CHICO, and (iv) via a B-11+ Te-130 fusion-evaporation reaction with the HORUS gamma-ray array at the University of Cologne. The high-spin level schemes of Xe-135 and Ba-137 are considerably extended to higher energies. The 2058-keV (19/2(-)) state in Xe-135 is identified as an isomer, closing a gap in the systematics along the N = 81 isotones. Its half-life is measured to be 9.0(9) ns, corresponding to a reduced transition probability of B(E2,19/2(-) -> 15/2(-)) = 0.52(6) W.u. The experimentally deduced reduced transition probabilities of the isomeric states are compared to shell-model predictions. Latest shell-model calculations reproduce the experimental findings generally well and provide guidance to the interpretation of the new levels.
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14.
  • Čolović, P., et al. (författare)
  • Population of lead isotopes in binary reactions using a Rb 94 radioactive beam
  • 2020
  • Ingår i: Physical Review C. - 2469-9985. ; 102:5
  • Tidskriftsartikel (refereegranskat)abstract
    • We measured absolute cross sections for neutron transfer channels populated in the Rb94+Pb208 binary reaction. Cross sections have been extracted identifying directly the lead isotopes with the high efficiency MINIBALL γ-ray array coupled to a particle detector combined with a radioactive Rb94 beam delivered at Elab=6.2 MeV/nucleon by the HIE-ISOLDE facility. We observed sizable cross sections in the neutron-rich mass region, where the heavy partner acquires neutrons. A fair agreement between the measured cross sections with those from GRAZING calculations gives confidence in the cross-section predictions of more neutron-rich nuclei produced via a larger number of transferred nucleons.
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15.
  • Guimond, S., et al. (författare)
  • Vanadium oxide surfaces and supported vanadium oxide nanoparticles
  • 2006
  • Ingår i: Topics in catalysis. - : Springer Science and Business Media LLC. - 1022-5528 .- 1572-9028. ; 38:1-3, s. 117-125
  • Tidskriftsartikel (refereegranskat)abstract
    • The information obtained from the characterization of vanadium oxide single crystal surfaces is related to the study of vanadia nanoparticles supported on silica and alumina thin films, model systems for the so-called “supported monolayer vanadia catalysts”. It is found that these particles have properties similar to V2O3 surfaces, where the topmost V ions are involved in vanadyl groups and have a 5+ oxidation state. A vibrational spectroscopy investigation combined with DFT calculations show that the accepted interpretation of vibrational spectra from vanadia catalysts must be revised.
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16.
  • Morrison, L., et al. (författare)
  • Dealing with contaminants in Coulomb excitation of radioactive beams
  • 2020
  • Ingår i: 27th International Nuclear Physics Conference (INPC2019) 29 July - 2 August 2019, Glasgow, UK. - : IOP Publishing. - 1742-6588. ; 1643
  • Konferensbidrag (refereegranskat)abstract
    • Data analysis of the Coulomb excitation experiment of the exotic 206Hg nucleus, recently performed at CERN's HIE-ISOLDE facility, needs to account for the contribution to target excitation due to the strongly-present beam contaminant 130Xe. In this paper, the contamination subtraction procedure is presented.
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17.
  • Morrison, L., et al. (författare)
  • Quadrupole and octupole collectivity in the semi-magic nucleus 20680Hg126
  • 2023
  • Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693. ; 838
  • Tidskriftsartikel (refereegranskat)abstract
    • The first low-energy Coulomb-excitation measurement of the radioactive, semi-magic, two proton-hole nucleus 206Hg, was performed at CERN's recently-commissioned HIE-ISOLDE facility. Two γ rays depopulating low-lying states in 206Hg were observed. From the data, a reduced transition strength B(E2; 2+1 → 0+1) = 4.4(6) W.u. was determined, the first such value for an N=126 nucleus south of 208Pb, which is found to be slightly lower than that predicted by shell-model calculations. In addition, a collective octupole state was identified at an excitation energy of 2705 keV, for which a reduced B(E3) transition probability of 30+10-30 W.u. was extracted. These results are crucial for understanding both quadrupole and octupole collectivity in the vicinity of the heaviest doubly-magic nucleus 208Pb, and for benchmarking a number of theoretical approaches in this key region. This is of particular importance given the paucity of data on transition strengths in this region, which could be used, in principle, to test calculations relevant to the astrophysical r-process.
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18.
  • Morrison, L., et al. (författare)
  • Quadrupole deformation of Xe 130 measured in a Coulomb-excitation experiment
  • 2020
  • Ingår i: Physical Review C. - 2469-9985. ; 102:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Low-lying states in the isotope Xe130 were populated in a Coulomb-excitation experiment performed at CERN's HIE-ISOLDE facility. The magnitudes and relative signs of seven E2 matrix elements and one M1 matrix element coupling five low-lying states in Xe130 were determined using the semiclassical coupled-channel Coulomb-excitation least-squares search code gosia. The diagonal E2 matrix elements of both the 21+ and 41+ states were extracted for the first time. The reduced transition strengths are in line with those obtained from previous measurements. Experimental results were compared with the general Bohr Hamiltonian with the microscopic input from mean-field theory utilizing universal nuclear energy density functional (UNEDF0), shell-model calculations using the GCN50:82 and SN100PN interactions, and simple phenomenological models (Davydov-Filippov and γ-soft). The extracted shape parameters indicate triaxial-prolate deformation in the ground-state band. In general, good agreement between theoretical predictions and experimental values was found, while neither phenomenological model was found to provide an adequate description of Xe130.
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19.
  • Tesi, B., et al. (författare)
  • Targeted high-throughput sequencing for genetic diagnostics of hemophagocytic lymphohistiocytosis
  • 2015
  • Ingår i: Genome Medicine. - : Springer Science and Business Media LLC. - 1756-994X. ; 7:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Hemophagocytic lymphohistiocytosis (HLH) is a rapid-onset, potentially fatal hyperinflammatory syndrome. A prompt molecular diagnosis is crucial for appropriate clinical management. Here, we validated and prospectively evaluated a targeted high-throughput sequencing approach for HLH diagnostics. Methods: A high-throughput sequencing strategy of 12 genes linked to HLH was validated in 13 patients with previously identified HLH-associated mutations and prospectively evaluated in 58 HLH patients. Moreover, 2504 healthy individuals from the 1000 Genomes project were analyzed in silico for variants in the same genes. Results: Analyses revealed a mutation detection sensitivity of 97.3 %, an average coverage per gene of 98.0 %, and adequate coverage over 98.6 % of sites previously reported as mutated in these genes. In the prospective cohort, we achieved a diagnosis in 22 out of 58 patients (38 %). Genetically undiagnosed HLH patients had a later age at onset and manifested higher frequencies of known secondary HLH triggers. Rare, putatively pathogenic monoallelic variants were identified in nine patients. However, such monoallelic variants were not enriched compared with healthy individuals. Conclusions: We have established a comprehensive high-throughput platform for genetic screening of patients with HLH. Almost all cases with reduced natural killer cell function received a diagnosis, but the majority of the prospective cases remain genetically unexplained, highlighting genetic heterogeneity and environmental impact within HLH. Moreover, in silico analyses of the genetic variation affecting HLH-related genes in the general population suggest caution with respect to interpreting causality between monoallelic mutations and HLH. A complete understanding of the genetic susceptibility to HLH thus requires further in-depth investigations, including genome sequencing and detailed immunological characterization.
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20.
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21.
  • Arapoglu, S., et al. (författare)
  • Multi-spin giants
  • 2004
  • Ingår i: Phys. Rev.. ; D69, s. 106006-
  • Tidskriftsartikel (refereegranskat)
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22.
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23.
  • Fedorov, A. V., et al. (författare)
  • Insight into the Temperature Evolution of Electronic Structure and Mechanism of Exchange Interaction in EuS
  • 2021
  • Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 12:34, s. 8328-8334
  • Tidskriftsartikel (refereegranskat)abstract
    • Discovered in 1962, the divalent ferromagnetic semiconductor EuS (TC = 16.5 K, Eg = 1.65 eV) has remained constantly relevant to the engineering of novel magnetically active interfaces, heterostructures, and multilayer sequences and to combination with topological materials. Because detailed information on the electronic structure of EuS and, in particular, its evolution across TC is not well-represented in the literature but is essential for the development of new functional systems, the present work aims at filling this gap. Our angle-resolved photoemission measurements complemented with first-principles calculations demonstrate how the electronic structure of EuS evolves across a paramagnetic-ferromagnetic transition. Our results emphasize the importance of the strong Eu 4f-S 3p mixing for exchange-magnetic splittings of the sulfur-derived bands as well as coupling between f and d orbitals of neighboring Eu atoms to derive the value of TC accurately. The 4f-3p mixing facilitates the coupling between 4f and 5d orbitals of neighboring Eu atoms, which mainly governs the exchange interaction in EuS.
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24.
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25.
  • Kalem, S., et al. (författare)
  • Si measurements : SiOx on Si
  • 2017
  • Ingår i: Joint International EUROSOl Workshop and International Conference on Ultimate Integration on Silicon-ULIS, EUROSOI-ULIS 2017 - Proceedings. - 2472-9132. - 9781509053131 ; , s. 235-238
  • Konferensbidrag (refereegranskat)abstract
    • We review the results of silicon measurements, which we have performed on suboxide SiOx formed on n and p type Si wafers with different surface textures. Localized vibrational modes through Raman and FTIR, light emission properties by photoluminescence (PL), energy critical points for optical transitions, excited state dynamics and non-linear electrical properties can be used as effective methods in investigating thin oxide layers on Si. Infrared vibrational spectrum of Si-O-Si bondings in terms of transverse-optic (TO) and longitudinal-optic (LO) phonons indicating that disorder induced LO-TO optical mode coupling can be an effective tool in assessing the structural quality of the SiOx. Excited carrier dynamics and switching mechanisms can provide critical information about electronic quality of sub oxides for applications in CMOS circuits.
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26.
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27.
  • Kaya, S., et al. (författare)
  • Formation of an ordered ice layer on a thin silica film
  • 2007
  • Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 111:2, s. 759-764
  • Tidskriftsartikel (refereegranskat)abstract
    • Adsorption of water on a thin silica film grown on a Mo(112) single crystal was studied by temperature-programmed desorption, infrared reflection absorption spectroscopy, and photoelectron spectroscopy using synchrotron radiation. Water does not dissociate on the defect-free oxygen-terminated silica surface. In contrast to adsorption at 100 K, where water follows a zero-order desorption kinetics, water adsorbed at 140 K exhibits a pseudo-first-order kinetics and induces a strong blue shift of the silica phonon. Even larger spectral changes were observed for D2O adsorption. The results were rationalized in terms of the formation of an amorphous solid water film at 100 K and a crystalline ice monolayer film at 140-150 K. This film is well-ordered as revealed by low-energy electron diffraction showing a c(2 x 2) superstructure with respect to the silica substrate.
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28.
  • Kaya, S., et al. (författare)
  • Formation of one-dimensional molybdenum oxide on Mo(112)
  • 2008
  • Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 602:21, s. 3338-3342
  • Tidskriftsartikel (refereegranskat)abstract
    • The atomic structure of a reconstructed Mo(112)-O(2 x 3) surface has been revisited using photoelectron spectroscopy with synchrotron radiation, scanning tunneling microscopy, infrared reflection absorption spectroscopy and density functional theory. In contrast to previous models, the results are rationalized in terms of the formation of one-dimensional, Mo=O terminated molybdenum oxide involving corner sharing distorted [MoO(6)] octahedra on the (1 x 3) reconstructed Mo(112) surface.
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29.
  • Kaya, S., et al. (författare)
  • Ice-assisted preparation of silica-supported vanadium oxide particles
  • 2007
  • Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 111:14, s. 5337-5344
  • Tidskriftsartikel (refereegranskat)abstract
    • Vanadium oxide particles were prepared by physical vapor deposition of vanadium in oxygen ambient onto ice-precovered well-ordered silica thin films. Morphology, electronic structure, and vibrational properties of the vanadia deposits were studied by scanning tunneling microscopy, X-ray photoelectron spectroscopy, temperature-programmed desorption, and infrared reflection absorption spectroscopy. The results show that the ice behaves as an oxidative agent, that favors vanadium oxidation up to V4+, and as a buffer layer that precludes strong interaction of the V adatoms with the silica film. At room temperature, upon desorption of the unreacted water, nanosized particles of vanadia hydroxide-like gel, containing V-OH and, to a lesser extent, vanadyl (VO) species, are formed. Vacuum annealing at 550 K leads to the total dehydration and partial reduction of the particles to V2O3, which expose the V-terminated surface. Subsequent reoxidation in 10(-6) mbar of O-2 irreversibly transforms the surface to the VO terminated, that is, the same as for the reactive deposition onto the clean silica surface. The results suggest that the structure of silica-supported vanadia catalysts is determined by a calcination step and should be considered under low oxygen pressure conditions as vanadium sesquioxide nanoparticles with the VO terminated surface.
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30.
  • Kaya, S., et al. (författare)
  • On the geometrical and electronic structure of an ultra-thin crystalline silica film grown on Mo(112)
  • 2007
  • Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 601:21, s. 4849-4861
  • Tidskriftsartikel (refereegranskat)abstract
    • The atomic structure of a well-ordered silica film grown on a Mo(112) single crystal substrate is discussed in detail using the experimental and theoretical results available to date. New photoelectron spectroscopy results using synchrotron radiation and ultraviolet spectroscopy data are presented. The analysis unambiguously shows that the ultra-thin silica film consists of a two-dimensional network of corner-sharing [SiO4] tetrahedra chemisorbed on the unreconstructed Mo(112) surface. The review also highlights the important role of theoretical calculations in the determination of the atomic structure of the silica films and in interpretation of experimental data.
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31.
  • Lu, J. -L, et al. (författare)
  • Formation of one-dimensional crystalline silica on a metal substrate
  • 2006
  • Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 600:13, s. L164-L168
  • Tidskriftsartikel (refereegranskat)abstract
    • We have observed formation of one-dimensional silica structures of 0.5 nm in width on Mo(112) single crystal surface. Combination of high-resolution scanning tunneling microscopy, photoelectron and infrared spectroscopy, and density functional theory provides strong evidence for formation of paired rows of corner sharing [SiO4] tetrahedra chemisorbed on a metal substrate.
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32.
  • Lu, J. -L, et al. (författare)
  • Low temperature CO induced growth of Pd supported on a monolayer silica film
  • 2006
  • Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 600:12, s. L153-L157
  • Tidskriftsartikel (refereegranskat)abstract
    • Nucleation, growth and sintering of Pd deposited on an ultra-thin silica film were studied by scanning tunneling microscopy and infrared reflection absorption spectroscopy. No preferential nucleation of Pd on the silica surface was observed both at 90 and 300 K deposition. When adsorbed on Pd clusters formed at 90 K, CO causes a strong sintering effect even at this temperature. The results are rationalized on the basis of a high mobility of Pd carbonyl-like species on the silica film. At a given Pd coverage, the extent of CO induced sintering cannot be achieved by annealing in vacuum. In addition, vacuum sintering, which commences above 700 K, goes simultaneously with interdiffusion of Pd and support.
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33.
  • Lu, J. -L., et al. (författare)
  • Structure, thermal stability, and CO adsorption properties of Pd nanoparticles supported on an ultra-thin SiO2 film
  • 2007
  • Ingår i: Surface review and letters. - 0218-625X. ; 14:5, s. 927-934
  • Tidskriftsartikel (refereegranskat)abstract
    • Nucleation, growth, and thermal stability of Pd particles vapor-deposited on an ultra-thin crystalline silica film grown on Mo(112) have been studied by scanning tunneling microscopy, X-ray photoelectron spectroscopy, infrared reflection absorption spectroscopy, and temperature-programmed desorption of CO. No preferential nucleation of Pd on the silica film is found at room temperature deposition: the hemispherical Pd nanoparticles are homogenously dispersed on the support at all coverages studied (0.01-1ML(mono layer)). The Pd particles are resistant toward sintering up to 700K as judged by STM; however, CO adsorption studies have revealed surface chemical modification at temperatures as low as 550K. Strong morphological changes are observed above 800K (ultimately resulting in elongated rectangular islands at similar to 1000 K), which is accompanied by strong alterations of CO adsorption properties. The results are rationalized in terms of Pd and Mo substrate interdiffusion at elevated temperatures, while the silica film basically preserves its structure.
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34.
  • Sahin, O, et al. (författare)
  • International Multi-Specialty Expert Physician Preoperative Identification of Extranodal Extension n Oropharyngeal Cancer Patients using Computed Tomography: Prospective Blinded Human Inter-Observer Performance Evaluation
  • 2024
  • Ingår i: medRxiv : the preprint server for health sciences. - : Cold Spring Harbor Laboratory.
  • Tidskriftsartikel (refereegranskat)abstract
    • BackgroundExtranodal extension (ENE) is an important adverse prognostic factor in oropharyngeal cancer (OPC) and is often employed in therapeutic decision making. Clinician-based determination of ENE from radiological imaging is a difficult task with high inter-observer variability. However, the role of clinical specialty on the determination of ENE has been unexplored.MethodsPre-therapy computed tomography (CT) images for 24 human papillomavirus-positive (HPV+) OPC patients were selected for the analysis; 6 scans were randomly chosen to be duplicated, resulting in a total of 30 scans of which 21 had pathologically-confirmed ENE. 34 expert clinician annotators, comprised of 11 radiologists, 12 surgeons, and 11 radiation oncologists separately evaluated the 30 CT scans for ENE and noted the presence or absence of specific radiographic criteria and confidence in their prediction. Discriminative performance was measured using accuracy, sensitivity, specificity, area under the receiver operating characteristic curve (AUC), and Brier score for each physician. Statistical comparisons of discriminative performance were calculated using Mann Whitney U tests. Significant radiographic factors in correct discrimination of ENE status were determined through a logistic regression analysis. Interobserver agreement was measured using Fleiss’ kappa.ResultsThe median accuracy for ENE discrimination across all specialties was 0.57. There were significant differences between radiologists and surgeons for Brier score (0.33 vs. 0.26), radiation oncologists and surgeons for sensitivity (0.48 vs. 0.69), and radiation oncologists and radiologists/surgeons for specificity (0.89 vs. 0.56). There were no significant differences between specialties for accuracy or AUC. Indistinct capsular contour, nodal necrosis, and nodal matting were significant factors in regression analysis. Fleiss’ kappa was less than 0.6 for all the radiographic criteria, regardless of specialty.ConclusionsDetection of ENE in HPV+OPC patients on CT imaging remains a difficult task with high variability, regardless of clinician specialty. Although some differences do exist between the specialists, they are often minimal. Further research in automated analysis of ENE from radiographic images is likely needed.
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35.
  • Sierka, M., et al. (författare)
  • Interplay between theory and experiment in the quest for silica with reduced dimensionality grown on a Mo(112) surface
  • 2006
  • Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614 .- 1873-4448. ; 424:1-3, s. 115-119
  • Tidskriftsartikel (refereegranskat)abstract
    • The stability of ordered one- and two-dimensional silica structures formed on a Mo(112) surface as a function of silicon coverage and oxygen pressure (phase diagram) is derived from density functional theory. At elevated oxygen pressures formation of a new, previously not considered structure of two-dimensional silica film is predicted. It contains additional oxygen atoms adsorbed directly on the Mo(112) surface underneath a two-dimensional network of corner sharing [SiO4] tetrahedra. The existence of the new phase is confirmed experimentally using infrared reflection absorption spectroscopy and X-ray photoelectron spectroscopy.
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36.
  • Stacchiola, D. J., et al. (författare)
  • Growth of stoichiometric subnanometer silica films
  • 2008
  • Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 92:1
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a method to grow stoichiometric SiO(2) films of only similar to 0.6-0.9 nm in thickness on a metal substrate. Based on photoelectron and infrared spectroscopy studies, we conclude that the similar to 0.6-nm-thick silica films exhibit characteristics only observed for > 2.0-nm-thick films grown on conventional Si substrates. The films can be used as model oxides for fundamental studies and may have implications on the further miniaturization of metal-oxide-semiconductor transistors.
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37.
  • Todorova, T. K., et al. (författare)
  • Atomic structure of a thin silica film on a Mo(112) substrate : A combined experimental and theoretical study (vol 73, pg 165414, 2006)
  • 2006
  • Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 73:16
  • Tidskriftsartikel (refereegranskat)abstract
    • The atomic structure of the thin SiO2 film on a Mo(112) substrate has been determined based on a combination of density functional theory calculations and high-quality experimental data obtained from scanning tunneling microscopy, infrared reflection absorption spectroscopy, and x-ray photoelectron spectroscopy. The film consists of a honeycomblike, two-dimensional network of corner-sharing [SiO4] tetrahedra. One oxygen atom of each tetrahedron binds to the Mo(112) substrate and is located in a bridge position between Mo atoms located in rows protruding from the metal surface. The other three oxygen atoms form Si-O-Si bonds with the neighboring tetrahedra.
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38.
  • Todorova, T K, et al. (författare)
  • Atomic structure of a thin silica film on a Mo(112) substrate : A combined experimental and theoretical study
  • 2006
  • Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 73:16, s. 165414-
  • Tidskriftsartikel (refereegranskat)abstract
    • The atomic structure of the thin SiO2 film on a Mo(112) substrate has been determined based on a combination of density functional theory calculations and high-quality experimental data obtained from scanning tunneling microscopy, infrared reflection absorption spectroscopy, and x-ray photoelectron spectroscopy. The film consists of a honeycomblike, two-dimensional network of corner-sharing [SiO4] tetrahedra. One oxygen atom of each tetrahedron binds to the Mo(112) substrate and is located in a bridge position between Mo atoms located in rows protruding from the metal surface. The other three oxygen atoms form Si-O-Si bonds with the neighboring tetrahedra.
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39.
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40.
  • Weissenrieder, Jonas, et al. (författare)
  • Atomic structure of a thin silica film on a Mo(112) substrate : A two-dimensional network of SiO4 tetrahedra
  • 2005
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 95:7, s. 1-4
  • Tidskriftsartikel (refereegranskat)abstract
    • The structure of a thin single crystalline SiO2 film grown on Mo(112) has been studied by scanning tunneling microscopy, infrared reflection absorption spectroscopy, and x-ray photoelectron spectroscopy. In excellent agreement with the experimental results, density functional theory calculations show that the film consists of a two-dimensional network of corner sharing [SiO4] tetrahedra, with one oxygen of each tetrahedron binding to the protruding Mo atoms of the Mo(112) surface.
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41.
  • Östrom, Henrik, et al. (författare)
  • Probing the transition state region in catalytic CO oxidation on Ru
  • 2015
  • Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 347:6225, s. 978-982
  • Tidskriftsartikel (refereegranskat)abstract
    • Femtosecond x-ray laser pulses are used to probe the carbon monoxide (CO) oxidation reaction on ruthenium (Ru) initiated by an optical laser pulse. On a time scale of a few hundred femtoseconds, the optical laser pulse excites motions of CO and oxygen (O) on the surface, allowing the reactants to collide, and, with a transient close to a picosecond (ps), new electronic states appear in the OK-edge x-ray absorption spectrum. Density functional theory calculations indicate that these result from changes in the adsorption site and bond formation between CO and O with a distribution of OC-O bond lengths close to the transition state (TS). After 1 ps, 10% of the CO populate the TS region, which is consistent with predictions based on a quantum oscillator model.
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42.
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43.
  • Barzgar Vishlaghi, Mahsa, et al. (författare)
  • Accelerating water oxidation on BiVO 4 photoanodes via surface modification with Co dopants
  • 2023
  • Ingår i: Journal of Materials Chemistry A. - 2050-7488 .- 2050-7496. ; 11:31, s. 16648-16658
  • Tidskriftsartikel (refereegranskat)abstract
    • Despite the vast investigations on improving the photoelectrochemical performance of BiVO4 for water splitting, charge recombination in the near-surface region remains a challenge. In this study, we showed that the diffusion of Co2+ ions into the BiVO4 subsurface boosted the water oxidation activity and charge injection efficiency remarkably. The increase in the concentration of oxygen vacancies upon the incorporation of cobalt ions was shown by electron paramagnetic resonance (EPR) spectroscopy and confirmed by density functional theory (DFT) calculations. DFT calculations revealed that vanadium sites in the subsurface region were the most favorable sites for substitution with cobalt ions. Charge localization at surface oxygen vacancies was found less favorable in the presence of cobalt in the subsurface layer, eliminating surface recombination. This resulted in 4.25 times larger charge injection efficiency and 6.2 times higher photocurrent density at the potential of ∼0.6 V, as compared to pristine BiVO4. This enhancement was significantly larger as compared to CoOx-loaded BiVO4, indicating that the suppressed recombination at the surface and improved charge transfer kinetics obtained solely by CoOx deposition are not sufficient for enhanced activity of BiVO4. A longer charge carrier lifetime obtained upon cobalt incorporation was observed by transient absorption spectroscopy and verified the reduced rate of recombination.
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44.
  • Beye, M., et al. (författare)
  • Selective Ultrafast Probing of Transient Hot Chemisorbed and Precursor States of CO on Ru(0001)
  • 2013
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 110:18
  • Tidskriftsartikel (refereegranskat)abstract
    • We have studied the femtosecond dynamics following optical laser excitation of CO adsorbed on a Ru surface by monitoring changes in the occupied and unoccupied electronic structure using ultrafast soft x-ray absorption and emission. We recently reported [M. Dell'Angela et al. Science 339, 1302 (2013)] a phonon-mediated transition into a weakly adsorbed precursor state occurring on a time scale of >2 ps prior to desorption. Here we focus on processes within the first picosecond after laser excitation and show that the metal-adsorbate coordination is initially increased due to hot-electron-driven vibrational excitations. This process is faster than, but occurs in parallel with, the transition into the precursor state. With resonant x-ray emission spectroscopy, we probe each of these states selectively and determine the respective transient populations depending on optical laser fluence. Ab initio molecular dynamics simulations of CO adsorbed on Ru(0001) were performed at 1500 and 3000 K providing insight into the desorption process.
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45.
  • Bouchal, Johannes M., 1979- (författare)
  • Reconciling the stratigraphy and depositional history of the Lycian orogen-top basins, SW Anatolia
  • 2019
  • Ingår i: Palaeobiodiversity and Palaeoenvironments. - Heidelberg : Springer Science and Business Media LLC. - 1867-1594 .- 1867-1608. ; 99, s. 551-570
  • Tidskriftsartikel (refereegranskat)abstract
    • Terrestrial fossil records from the SW Anatolian basins are crucial both for regional correlations and palaeoenvironmental reconstructions. By reassessing biostratigraphic constraints and incorporating new fossil data, we calibrated and reconstructed the late Neogene and Quaternary palaeoenvironments within a regional palaeogeographical framework. The culmination of the Taurides in SW Anatolia was followed by a regional crustal extension from the late Tortonian onwards that created a broad array of NE-trending orogen-top basins with synchronic associations of alluvial fan, fluvial and lacustrine deposits. The terrestrial basins are superimposed on the upper Burdigalian marine units with a c. 7 myr of hiatus that corresponds to a shift from regional shortening to extension. The initial infill of these basins is documented by a transition from marginal alluvial fans and axial fluvial systems into central shallow-perennial lakes coinciding with a climatic shift from warm/humid to arid conditions. The basal alluvial fan deposits abound in fossil macro-mammals of an early Turolian (MN11–12; late Tortonian) age. The Pliocene epoch in the region was punctuated by subhumid/humid conditions resulting in a rise of local base levels and expansion of lakes as evidenced by marsh-swamp deposits containing diverse fossilmammal assemblages indicating late Ruscinian (lateMN15; late Zanclean) age. A second pulse of extension, accompanied by regional climatic  changes, prompted subsequent deepening of the lakes as manifested by thick and laterally extensive carbonate successions. These lakes, which prevailed c. 1 myr, later shrank due to renewed progradation of alluvial fans and eventually filled up and dried out, reflected by marsh-swamp deposits at the top of a complete lacustrine succession that contains diverse micro-mammal assemblages indicating a latest Villanyian (MN17; Gelasian) age. A third pulse of tectonic reorganisation and associated extension dissected the basins into their present-day configuration from the early Pleistocene onwards under warm/humid climatic conditions. The new age data provide means to correlate deposits across various basins in the region that help to place the basin development into a regional tectonic framework, which can be attributed to the consequence of the well-articulated regional phenomena of slab-tear/detachmentinduced uplift followed by crustal extension and basin formation (late Tortonian), the outward extension of the Aegean arc (early Pliocene) and eventually accompanied by westward extrusion of the Anatolian Plate (early Pleistocene).
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46.
  • Çakmak, Tolga, et al. (författare)
  • Novel Strategy for One-Step Production of Attenuated Ag-Containing AgCu/ZnO Antibacterial-Antifungal Nanocomposite Particles
  • 2020
  • Ingår i: Powder Metallurgy and Metal Ceramics. - : Springer Science and Business Media LLC. - 1068-1302 .- 1573-9066. ; 59:5-6, s. 261-270
  • Tidskriftsartikel (refereegranskat)abstract
    • Novel strategies have been developed to comply with Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH) regulations to provide the same performances for antibacterial and antifungal materials. The strategy for producing composite materials by attenuating the silver (Ag) content and a one-step production technique without minimizing the antibacterial and antifungal performance was developed. In this study, attenuated spherical Ag containing spherical AgCu/ZnO nanocomposite particles have been synthesized from an aqueous solution of silver nitrate (AgNO3), copper nitrate (Cu(NO3)2 · 3H2O), and zinc nitrate (Zn(NO3)2 · 7H2O) by a facile one-step ultrasonic spray pyrolysis and hydrogen reduction (USP-HR) method. Characterization of AgCu/ZnO nanocomposite particles was carried out by various techniques such as X-ray diffraction analysis (XRD), scanning electron microscopy (FEG-SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The structural analysis showed that AgCu/ZnO nanocomposites were composed of face-centered cubic Ag, face-centered cubic Cu, and hexagonal ZnO phases. Antibacterial and antifungal properties of nanocomposite particles against Escherichia coli and Aspergillus niger were investigated by agar medium and broth medium methods. The obtained results indicate that produced nanocomposite particles possess antibacterial and antifungal properties (100%). The attenuated Ag in the AgCu/ZnO nanocomposite particles has the usage potential in different areas of the textile industry. In particular, the research on utilizing this nanocomposite in hand-made fiber production as an additive is of very high interest.
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47.
  • Cserni, G, et al. (författare)
  • Consistency in recognizing microinvasion in breast carcinomas is improved by immunohistochemistry for myoepithelial markers.
  • 2016
  • Ingår i: Virchows Archiv: an international journal of pathology. - : Springer Science and Business Media LLC. - 1432-2307. ; 468:4, s. 473-481
  • Tidskriftsartikel (refereegranskat)abstract
    • Microinvasion is the smallest morphologically identifiable stage of invasion. Its presence and distinction from in situ carcinoma may have therapeutic implications, and clinical staging also requires the recognition of this phenomenon. Microinvasion is established on the basis of several morphological criteria, which may be difficult and not perfectly reproducible among pathologists. The aim of this study was to assess the consistency of diagnosing microinvasion in the breast on traditional haematoxylin and eosin (HE) stained slides and to evaluate whether immunohistochemistry (IHC) for myoepithelial markers could improve this. Digital images were generated from representative areas of 50 cases stained with HE and IHC for myoepithelial markers. Cases were specifically selected from the spectrum of in situ to microinvasive cancers. Twenty-eight dedicated breast pathologists assessed these cases at different magnifications through a web-based platform in two rounds: first HE only and after a washout period by both HE and IHC. Consistency in the recognition of microinvasion significantly improved with the use of IHC. Concordance rates increased from 0.85 to 0.96, kappa from 0.5 to 0.85, the number of cases with 100 % agreement rose from 9/50 to 25/50 with IHC and the certainty of diagnosis also increased. The use of IHC markedly improves the consistency of identifying microinvasion. This corroborates previous recommendations to use IHC for myoepithelial markers to clarify cases where uncertainty exists about the presence of microinvasion. Microinvasive carcinoma is a rare entity, and seeking a second opinion may avoid overdiagnosis.
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48.
  • Dell'Angela, M., et al. (författare)
  • Real-Time Observation of Surface Bond Breaking with an X-ray Laser
  • 2013
  • Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 339:6125, s. 1302-1305
  • Tidskriftsartikel (refereegranskat)abstract
    • We used the Linac Coherent Light Source free-electron x-ray laser to probe the electronic structure of CO molecules as their chemisorption state on Ru(0001) changes upon exciting the substrate by using a femtosecond optical laser pulse. We observed electronic structure changes that are consistent with a weakening of the CO interaction with the substrate but without notable desorption. A large fraction of the molecules (30%) was trapped in a transient precursor state that would precede desorption. We calculated the free energy of the molecule as a function of the desorption reaction coordinate using density functional theory, including van der Waals interactions. Two distinct adsorption wells-chemisorbed and precursor state separated by an entropy barrier-explain the anomalously high prefactors often observed in desorption of molecules from metals.
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49.
  • Dell'Angela, M., et al. (författare)
  • Vacuum space charge effects in sub-picosecond soft X-ray photoemission on a molecular adsorbate layer
  • 2015
  • Ingår i: Structural Dynamics. - : AIP Publishing. - 2329-7778. ; 2:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Vacuum space charge induced kinetic energy shifts of O 1s and Ru 3d core levels in femtosecond soft X-ray photoemission spectra (PES) have been studied at a free electron laser (FEL) for an oxygen layer on Ru(0001). We fully reproduced the measurements by simulating the in-vacuum expansion of the photoelectrons and demonstrate the space charge contribution of the high-order harmonics in the FEL beam. Employing the same analysis for 400 nm pump-X-ray probe PES, we can disentangle the delay dependent Ru 3d energy shifts into effects induced by space charge and by lattice heating from the femtosecond pump pulse.
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50.
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